1. Technical Field
The present invention relates to a micro electromechanical system (MEMS) device, and more particularly to a MEMS device with at least a hollow region and a MEMS spring element with at least a hollow region.
2. Description of the Related Art
Micro electromechanical system (MEMS) technique has opened up a whole new technical field and industry. The MEMS technique has been widely used in inertial sensors, for example, accelerometers and gyroscopes. Generally, in these sensors, one end of a moveable structure of the sensor is fixed on a substrate by a MEMS spring element. As such, the moveable structure can has a reciprocating motion along a predetermined direction. The MEMS spring element is commonly made by stacking metal layers and oxide layers.
However, because thermal expansion coefficient of the metal layers is different from that of the oxide layers, the metal layers and the oxide layers will be thermally expanded to different degrees when a high-temperature manufacturing process of the MEMS spring element is carried out. Consequently, the MEMS spring element will be deformed, and thus and working performance of the MEMS spring element will be degraded.
What needed, therefore, is a new MEMS spring element and a new MEMS device that can overcome the above-mentioned shortcomings.